A report states that the cost of repairing a hybrid vehicle is falling even whil

Question

A report states that the cost of repairing a hybrid vehicle is falling even while typical repairs on conventional vehicles are getting more expensive. The most common hybrid repair, replacing the hybrid inverter assembly, had a mean repair cost of $3,927 in 2012. Industry experts suspect that the cost will continue to decrease given the increase in the number of technicians who have gained expertise on fixing gas-electric engines in recent months. Suppose a sample of 100 hybrid inverter assembly repairs completed in the last month was selected. The sample mean repair cost was $3,780 with the sample standard deviation of $600. Complete parts (a) and (b) below. a. Is there evidence that the population mean cost is less than $3,927? (Use a 0.10 level of significance.) State the null and alternative hypotheses Ho: z $ 3927 My

Explanation / Answer

You will have to use technology to solve the problem as normal t-tables don't specify df = 99' .05 one tailed value.

I used the following link to arrive at the P-Value of .008

http://www.socscistatistics.com/pvalues/tdistribution.aspx

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